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Fall fertility options
Fall nitrogen application
Nitrogen is typically the most yield-limiting nutrient, and it’s one of the largest input costs for corn production. Fall-applied nitrogen is at highest risk for loss through leaching or denitrification.
“This fall, consider the benefit of improved utilization efficiency gained by applying nitrogen closer to the time the crop uses it,” Wilson suggests. “Take the time to rethink the number of acres covered and your nitrogen application rate.”
For example, this past spring several fields with fall-applied nitrogen had leaching problems following excess spring moisture. Growers may not have lost as much of their investment if they had waited until spring to apply.
“Fall applications are largely driven by logistics and an effort to spread out the workload. If you have the equipment and manpower, it’s better to wait to apply nitrogen in the spring,” says Neal Hoss, DuPont Pioneer technical services manager in Illinois and Indiana. “If you don’t have the capacity for spring applications, target fields with the least amount of risk and use nitrogen inhibitors to minimize the potential loss of your nitrogen investment.”
Timing phosphorus and potassium application
To improve phosphorus and potassium management and maximize the return on your investment, consider precision soil sampling, such as management zone and grid sampling, in conjunction with variable-rate technology. The return on fertilizer investment is greatest for low-testing soils. With variable input prices, avoiding unnecessary fertilization of high-testing soils increases profitability.
Phosphorus and potassium fertilizers applied in the fall are more stable, offering less risk than fall-applied nitrogen. If you’re trying to reduce your spring workload, phosphorus and potassium fertilizer applications can easily be done in the fall, when weather and soil conditions are generally not as wet, which diminishes concerns about compaction.
If weather or a late harvest delays application, avoid applying phosphorus and potassium on frozen or snow-covered fields due to a high risk of loss with surface runoff. In such cases, application prior to planting in the spring is just as effective, as long as soil test levels are above the very low range.